Magnetic separating machines



March 1964 SEllCHlRO WATANABE ETAL MAGNETIC SEPARATING MACHINES 2 Sheets-Sheet 1 Filed Dec. 26, 1961 INVENTOR. SEIICHIRO WATANABE TOSHIO KOBAYASHI AND B HIROMITSU SHOJI [P /0m ZJHM United States Patent Ofiice 3,124,527 Patented Mar. 10, 1964 3,124,527 1 MAGNETIC SEPARATIING MACHWES Seiichiro Watanabe, Toshio Kobayashi, and- Hiromitsu Shoji, all of Tokyo, Japan, assignors to Japan Special Steel Company Limited, Tokyo, Japan, a corporation of Japan Filled Dec. 26, 1961, Ser. No. 161,782 Claims priority, application Japan Dec. 30, 196i) 6 Claims. ((Il. 209-218) The present invention relates to improvements in a magnetic separator of iron sand and other magnetic materials, and more particularly to a machine for selectively separating magnetic materials by combining in a flexible magnetic belt mechanical and physical separating effect and magnetic force to carry out the separation positively and effectively.

In heretofore known magnetic separators or magnetic concentrators of this kind use is made of magnet structures having a great number of permanent magnets or magnet structures which are magnetized and a common conveyor belt carrying ores or the material to be separated along the surface of the magnetic structures to effect separation by means of magnetic force so that the effects of magnets act indirectly and the magnetic lines of force developed from the magnetstructures could not be perfectly utilized for the separation of magnetic material.

According to the present invention the belt itself for carrying the ores or other material to be separated is made of a flexible magnetic material such as magnetic rubber magnetized to have a sufficient number of magnet poles so that the magnetic powders or granules to be separated can be more perfectly and positively attracted by the special magnetic belt as it acts directly.

The attractive force of a magnet is usually inversely proportional to the square of the distance from the magnet pole to the article to be attracted and when a material is adhered directly to magnet poles of the magnetic belt the attractive force increases intermittently and abruptly thoughthe magnetic force of the flexible magnetic belt itself is somewhat weaker than that of cast Alnico magnets orbariuin-ferrite sintered magnets, yet the attractive force of magnetic powders to the surface of conveyor.

belt is much greater in case of the flexible magnetic belt, in which magnetic materials are directly attracted to magnet poles, than that of the conventional magnetic separator wherein the attractive forces of magnets are applied to magnetic powders-on the surface of conveyor belt through a thickness of the belt indirectly.

For instance, in case of magnetic separation of iron sand the attractive force for iron particles in iron sand acts almost perfectly while on the other hand impurities adhere to the surface together with iron particles and also the latter are diflicult to be taken olf and collected.

According to the invention, in order to obviate the disadvantage the flexible magnetic belt is specially constructed and the conveyor is adjustably arranged to have V a suitable slope and is provided with water injection noz- .be explained hereinafter in detail.

' on at spaced relation.

For a better understanding of the invention reference is made to the accompanying drawings, in which FIG. 1 is a diagrammatic side elevation of a magnetic separator of the invention,

FIG. 2A and -B are sectional elevation and plan view respectively of an embodiment of the flexible magnetic belt,

FIG. 3 is a diagrammatic view of an embodiment of the magnetic take-01f device,

FIG. 4 is a sectional View showing another embodiment of the magnetic take-01f device in which a permanent magnet is associated with each soft pole shoe,

FlG. 5 is a partial sectional side view showing an embodiment of the magnetic'concentrating device, and

FIG. 6 represents curve diagrams illustrating the relation between the slope of the conveyor and yield, grades of concentrate and tailing.

Referring to FIG. 1 and FIGS. 2A and B, 1 represents a flexible magnetic belt of a substantial breadth having a suitable number of magnet poles provided there- The magnetic belt 1 may be made of a rubber belt as shown in -FIG. 2, wherein a suitable number of magnetic rubber pieces 2 are embedded therein at proper intervals.

Instead of embedding magnetic rubber pieces, the belt may be made as a whole of flexible rubber material mixed with ferrite powders and vulcanized and then magnetized at definite spaces to have alternately different poles of N and S.

' Alternatively the rubber magnet pieces 2 and nonmagnetic pieces 4 such as rubber pieces are attached alternately to the surface of a cloth belt 3 to form a flexible magnetic belt. The magnetic rubber pieces 2 are made of rubber mixed with ferrite powders for instance and magnetized to have N-S poles at each end alternately to show very sharp magnetic property to develop powerful attractive force. a

5 represents belt pulleys supported on the machine frame 6, which is secured adjustably to the pillar 7 fixed to the base 8 of the machine and the slope of the belt conveyor maybe adjusted by means of a suitable adjusting device 9 sliding along the groove 9. Such adjusting means may be constructed in any Way as desired, but the adjustable feature of the belt conveyor is one of the essential features of the invention. 10 represents a driving motor, 11 a speed reduction gear, 12 and 13 represent belt pulleys and 14 a power transmission belt.

v The present magnetic separator is provided with a suitable number of water injection nozzles 15 arranged along the upper side of the belt adjacent thereto. In order to take-off the concentrated. magnetic powders from the belt a magnetic take-off means 1617 as shown in FIG. 3 is provided 'at a suitable position along the lower side 'of' shown in FIG. 4, wherein 18 represents a number of permanent magnets having pole pieces 19 of soft iron with alternately different polarities N and S.

I Referring to FIG. 3, the magnetic forces act to takeoff the purified magnetic powders (concentrate) 21 attached to the surface of the magnetic belt 1 by the cooperation of N and S magnet pole pieces 19 with the alternate poles of N and S of the magnetic rubber pieces 2 on the belt 1 when the wheel 17 (FIG. 3) rotates. A water injection nozzle 22 is provided adjacent to the belt netic attraction of the magnetized portions or magnets 2 in the belt. I When demagnetized, the magnetic particles 21 may be easily washed off by the jet issuing from the pipe 22. The continued sweeping by the induced fields will often cause the magnetic particles to be repulsed from the belt, thus, assisting in the separation of the concentrated material from the belt.

The magnetic separator or concentrator of the invention can be operated at a suitable slope of the belt according to the kind and property of raw materials to be separated. The raw material such as iron sand is fed through a hopper or feeder 25 on the belt 1 which is supposed to be driven in the direction of arrow A. Then the magnetic particles are attracted to the belt and carried with it and the impurities in iron sand are washed off by the water issuing from the nozzles 15 and the concentrated iron sand is carried with the belt and is taken-off at the magnetic take-off device 1617.

In order to assist the separation of magnetic substances such as iron sand more effectively and to obtain better grade of concentrate, a magnetic separation device 23 (FIGS. 1 and is arranged adjacent to the back side of the upper magnetic belt conveyor 1 at a position opposite to the water injection nozzles 15. The magnetic separation device 23 is more clearly shown in FIG. 5, wherein 24 represents permanent magnets having pole pieces 25 of soft iron attached to each side thereof and energized to have N and S poles of alternately different polarities preferably to correspond with magnetic rubber pieces 2 of the belt 1. 26 represents non-magnetic piece such as wood or plastic material.

The operation of the magnetic separating device will be explained in the following:

When the magnetic rubber belt 1 advances in the direction of arrow A (FIG. 1) carrying raw material to be separated thereon and passes the position opposite to the. magnetic device 23 the magnetic particles are acted upon by the magnetic field between the poles of the permanent magnets and N and S poles of the rubbermagnet pieces 2 and the particles take the direction of the magnetic field which is alternately reversed in phase as the belt travels so that the magnetic particles advance together with the traversing belt by alternately turning over and again tumbling over-and-over periodically and are subjected to the washing effect of the water jet so that impurities can be very clearly washed off and very high grade concentrate is carried by the magnetic belt and when they come to the position of the magnetic take-off device 1617, the very high grade concentrate can be taken off by the magnetic attraction, repulsion or demagnetization of the attracted magnetic powders.

The action of the magnetic separating device 23 and the magnetic rubber pieces 2 of the belt on magnetic powders is very interesting in that the magnetic particles stand up on the surface of the belt by the magnetic lines of force caused by the cooperation of the magnet poles of rubber magnet pieces and the alternate N and S poles of the permanent magnets 24 and as the direction of flux is reversed by the travel of the belt the magnetic particles are turned over and water jet acts on the standing and upset particles so that the impurities can be very well eliminated and very excellent concentrate of high quality can be obtained.

Thus, it can be seen that as the belt traverses the magnetic separator 23, the magnetic field established by the magnets 25 therein will, in cooperation with the magnetic fields established in the magnets 2 in the belts surface, cause a periodic variation in the direction of the magnetic field. Therefore, as the belt traverses the separator 23, the magnetic field will reverse in direction as the magnets 4 in the separator 23 and the magnets in the belt are periodically aligned and misaligned. Since the particles will align themselves within the fields of force in the magnetic field, the particles will be subjected to position reversal such as tumbling. Thus, for example, a single particle will be aligned on'the surface of the belt, then will align itself standing on end with the magnetic field and finally tumble over as the field reverses. 'The continued agitation of the particles exposes all the surfaces thereof to the output of the water jet and further ensures that impurities are not trapped beneath particles which might be the case if the particles were held stationary on the belt. For this reason, the concentration by washing away of the impurities can be effective with startling increases in processing speeds.

The magnetic separator of the invention as shown in FIG. 1 may be operated in a reverse direction as shown by thearrow B, i.e. in the same direction as the natural flow of water jet and in this case the upper surface of the belt is used as a rough separation and the lower surface of the belt may be used as a fine separation. But the'belt is usually driven in the direction of the arrow A, i.e. in the reverse direction to the flowing water. In this case the slope of the belt has an important relation to the grade of the concentrate to be obtained. An example of the relation is shown by the curve A in FIG. 6, wherein the ordinate shows the grade of concentrate and abscissa, the angle of inclination of the belt in degrees and the curve B shows the grade of tailing. It will be seen that the maximum grade of concentrate and tailing can be obtained at a slope from 50 to 60 showing that the highest grade of concentrate is 97.5 weight percent and the grade of tailing is 1.0 weight percent at the slope of 50 using the sample of beach iron sand of 5 to 7% grade at the rate of feed, 30 ton/hour and belt speed at m./min.

An example of the present machine and a result of experiment of effecting separation of iron sand are shown in the following:

Breadth of magnetic rubber belt 1,500 mm. Size of rubber magnetic piece- Breadth 8 mm.

Thickness 4 mm. Length 1,450 mm. Flux density on the surface of the rubber magnet piece 200 gauss. Pulp density 20% Magnetic grade of raw ore 15% Quantity of ore feed 30 tons/ hours. Speed of the magnetic rubber belt 100 m./min. Slope of the belt .50". Magnetic field .of the magnetic separating device 950 gauss. Magnetic field of magnetic take-off device 1,000 gauss. Raw ore Beach iron sand. Results of separation- Concentrate 99.3%. Tailing 0.4%

Excellent results were obtained.

What we claim is:

1. A'magnetic separator for magnetic particles which comprises an endless belt conveyor having upper and lower runs arranged in an inclined position, the conveyorbelt being made of flexible material mixed with ferrite powders and magnetized to have a desired number of spaced apart magnetic poles, said spaced apart magnetic poles comprising north and south poles in alternately different polarities, a driving means for said flexible magnetic belt, water injection nozzles-arranged; above the upper run of said belt at the upper end of the incline and positioned to spray upon the upper surface of the upper run of said belt, a. magnetic take-01f device mounted adjacent the lower run of said belt to remove the'particles held on the belt surface, said device comprising means for establishing magnetic fields cancelling the attractive fields of said magnetic poles in said belt, and means for adjusting the slope of the belt.

2. A magnetic separator according to claim 1, which comprises a magnetic agitating device arranged adjacent an under side, of the upper run of the flexible magnetic belt in a position opposite to said water injection nozzles, said magnetic agitating device being made of a plurality of magnets having pole pieces of alternately different polarities to cooperate with the magnetic poles of the conveyor belt to cause alternately different magnetic fields when the belt travels, thereby agitating said magnetic particles on the surface of the belt as the field and the particles aligned therewith are reversed, during which the water from said nozzle acts to separate impurities from the magnetic particles.

3. A magnetic separator according to claim 1, wherein the magnetic take-off device comprises a number of permanent magnets arranged at a spaced relation with each other and provided with pole pieces of alternately different polarities facing the magnetic belt, said permanent magnets being spaced adjacent said belt on the back side of the lower run thereof, and a revolving wheel positioned opposite said permanent magnets and on the other side of said belt, said revolving wheel having a number of soft iron poles projecting from its periphery adjacent to the magnetic belt and opposite said permanent magnets to cooperate with said permanent magnets and the magnet poles of the rubber magnet pieces of the belt acting to magnetically remove the concentrate from the magnetic belts and a water injection nozzle positioned adjacent the lower side of the lower run of said belt and longitudinally adjacent said revolving wheel on the side thereof facing toward the lower end of the incline cooperating with said magnetic take-01f device.

4. A magnetic separator according to claim 1, wherein the conveyor belt consists of a flexible rubber belt having pieces of magnetic rubber embedded therein with a definite space between them and magnetized to have alternately 6 different magnetic poles N and S, said magnetic rubber pieces consisting of rubber material mixed with ferrite powders.

5. A magnetic separator according to claim 1, wherein the conveyor belt consists of a cloth belt having pieces of magnetic rubber and non-magnetic rubber alternately adhered thereto and said magnetic rubber pieces are magnetized to have alternately different N and S poles.

6. A magnetic separator comprising an endless belt conveyor having upper and lower runs arranged in an inclined position, said belt comprising a flexible material having a plurality of spaced apart magnetized strips extending across said belt, each strip having a north and south pole to provide magnetic fields to hold magnetic particles on the surface of said belt, means for driving said belt, means for spraying water onto the material on said belt, said spraying means being positioned adjacent and above the upper run of said belt and at the upper end of the incline, means for agitating said particles to expose the particle surfaces to the spray, said last named means comprising a plurality of magnets of alternating polarity positioned adjacent the underside of the upper run of said belt and opposite said spraying means to establish a mag netic field at the belt surface, said field being a composite field established by said magnets in said agitating means and said magnetized strips and said composite field changing direction as said belt moves past said agitating means to change the positions of the particles as the particles align themselves with the changing field and, thus, to agitate said particles exposing the surfaces thereof to the water spray, and means for adjusting the slope of the conveyor belt.

References Cited in the file of this patent UNITED STATES PATENTS 751,150 Dean Feb. 2, 1904 2,759,606 Nippert Aug. 21, 1956 3,042,205 Merwin July 3, 1962 

1. A MAGNETIC SEPARATOR FOR MAGNETIC PARTICLES WHICH COMPRISES AN ENDLESS BELT CONVEYOR HAVING UPPER AND LOWER RUNS ARRANGED IN AN INCLINED POSITION, THE CONVEYOR BELT BEING MADE OF FLEXIBLE MATERIAL MIXED WITH FERRITE POWDERS AND MAGNETIZED TO HAVE A DESIRED NUMBER OF SPACED APART MAGNETIC POLES, SAID SPACED APART MAGNETIC POLES COMPRISING NORTH AND SOUTH POLES IN ALTERNATLEY DIFFERENT POLARITIES, A DRIVING MEANS FOR SAID FLEXIBLE MAGNETIC BELT, WATER INJECTION NOZZLES ARRANGED ABOVE THE UPPER RUN OF SAID BELT AT THE UPPER END OF THE INCLINE AND POSITIONED TO SPRAY UPON THE UPPER SURFCE OF THE UPPER RUN OF SAID BELT, A MAGNETIC TAKE-OFF DEVICE AMOUNT ADJACENT THE LOWER RUN OF SAID BELT TO REMOVE THE PARTICLES HELD ON THE BELT SURFACE, SAID DEVICE COMPRISING MEANS FOR ESTABLISHING MAGNETIC FIELDS CANCELLING THE ATTRACTIVE FIELDS OF SAID MAGNETIC POLES IN SAID BELT AND MEANS FOR ADJUSTING THE SLOPE OF THE BELT. 